1. Technical Field
The present invention relates to an array microphone device, and, more specifically, to an array microphone device having a sensitivity correction function.
2. Background Art
An array microphone device has been conventionally known as one of directional microphones. The array microphone device, in which a plurality of microphones is arranged, executes the signal processing on the input sound so as to be able to acquire spatial information of a sound that cannot be obtained by a single microphone. Thereby, the directivity control is applied, and estimation can be made for the direction from which the sound is approaching. In recent years, the array microphone device has been used in the directivity control for picking up the sound in a remote sound pickup or an in-car hands-free call system at a high S/N (signal-to-noise) ratio.
An array microphone device of this type, which has been known, has such a function (a sensitivity correction function) to correct automatically sensitivity of each of the microphone units, constituting the microphone array, so as to have the identical characteristics (refer to Publication of JP-A-H07-131886, for example). In such an array microphone device, a sensitivity correction means for correcting the sensitivity is provided at the stage prior to a directivity synthesis means for executing the directivity synthesis. Then, the directivity synthesis means operates normally based on the condition such that all of incoming signals are kept at the same level even in the case where the sensitivity of each microphone unit or the sensitivity of associated circuits such as a microphone amplifier (which are simply referred to collectively as the microphone unit sensitivity) are not identical for the reasons of chronological change, manufacturing process, and so on.